1. Field of the Invention
The present invention relates to a method for determining the recombination rate of minority carriers at boundary surfaces between semiconductors and other substances in which a first half cell is attached to the front side of a semiconductor crystal body, a second half cell is applied to the rear side of the semiconductor crystal body and both half cells can be filled with an electrolyte, in which at least a second half cell contains an electrode and is filled with the electrolyte in contact with the electrode and the rear side of the semiconductor crystal body, in which at least the electrode in the second half cell is connected to the semiconductor crystal body via a voltage source and via an ohmic contact, in which a DC voltage is applied to the voltage source so that an inhibiting space charge zone is generated at the rear side of the semiconductor crystal body, and in which the front side is illuminated with a light source.
2. Description of the Prior Art
The boundary surface recombination speed S is a measure for the speed with which minority carriers disappear at a boundary surface through recombination (See S. M. Sze, Physics of Semiconductors, Whiley-Interscience Publishers). It is proportional to the boundary surface state density N, i.e. the density of electrically-active states in the band gap.
The boundary surface recombination speed S or the boundary surface state density N is one of the important parameters for characterizing boundary surface such as, for example, the boundary surface Si--SiO.sub.2 with respect to their electrical properties. The electrical properties and the long-term behavior of transistors in integrated circuits are influenced as a result thereof. In addition, the boundary surface recombination speed S can also be employed as a monitoring quantity when monitoring layer manufacturing methods in the fabrication of microelectronic components.
Deep level transient spectroscopy (DLTS) can be employed for the calculation of the parameter S; such as method is set forth in the article by N. M. Johnson, J. Vac, Sci, Techn., Vol. 21, 1982, p. 303. To that end, a metal-oxide-semiconductor (MOS) capacitor must be applied onto the semiconductor. An alternating voltage that is superposed on a DC voltage is applied to the metal gate, so that the boundary state density and recombination speed can be calculated therefrom.
A second method of calculating the recombination speed measures the chronological change of the capacitance of such a MOS capacitor, the cause of this change being thermal generation of electron-hole pairs (See K. S. Rabbani, et al, Solid State Electronics, Vol. 24, 1981, p. 661.).
The mentioned methods require special test structures and are highly time consuming, even given measurement with low topical resolution.